Drone encroachment avoidance monitor

ABSTRACT

Disclosed are examples of systems, apparatus, methods and computer program products for locating unmanned aerial vehicles (UAVs). A region of airspace may be scanned with two scanning apparatuses. Each scanning apparatus may include one or more directional Radio Frequency (RF) antennae. The two scanning apparatuses may have different locations. Radio frequency signals emitted by a UAV can be received at each of the two scanning apparatuses. The received radio frequency signals can be processed to determine a first location of the UAV.

PRIORITY DATA

This patent document is a continuation of and claims the benefit of priority under 35 U.S.C. § 120 of U.S. patent application Ser. No. 14/723,299, titled “Drone Encroachment Avoidance Monitor”, by Timothy Just, filed 27 May 2015, (Attorney Docket No. JUSTP001), which claims priority to U.S. Provisional Patent Application No. 62/129,672, titled “Drone Encroachment Avoidance Monitor”, by Timothy Just, filed 6 Mar. 2015, (Attorney Docket No. JUSTP001P). Both U.S. patent application Ser. No. 14/723,299 and U.S. Provisional Patent Application No. 62/129,672 are incorporated herein by reference in their entirety for all purposes.

TECHNICAL FIELD

This patent document generally relates to unmanned aerial vehicles (UAVs). More specifically, this patent document discloses techniques for detecting and/or locating UAVs.

BACKGROUND

A diverse assortment of UAVs can be obtained by a wide variety of users in the marketplace. Some of such UAVs can be piloted with little skill and can reach a broad range of locations.

SUMMARY

Methods, systems, apparatuses, and computer program products for detecting and/or locating unmanned aerial vehicles (UAVs) are disclosed herein. Some of the disclosed techniques may be used for detecting small UAVs, such as those weighing approximately 10 pounds or less, sometimes referred to as micro-UAVs, micro-drones, quad-copters or multi-rotors, and referred to herein below as micro-UAVs. Detecting and locating UAVs may enhance the safety of secure locations such as airports, military bases, and other landmarks.

Among various embodiments disclosed herein is a method of locating UAVs. The method involves scanning a region of airspace with two scanning apparatuses. Each scanning apparatus may include one or more directional Radio Frequency (RF) antennae. The two scanning apparatuses may have different locations. Radio frequency signals emitted by a UAV can be received at each of the two scanning apparatuses. The received radio frequency signals can be processed to determine a location of the UAV.

Also described is an apparatus for detecting UAVs. The apparatus may include a rotatable structure configured to rotate in a horizontal plane about a vertical axis. A first array of one or more directional antennae may be connected with the rotatable structure. The first array may be statically deployed along the vertical axis. A second array of one or more directional antennae may be connected with the rotatable structure. The second array may be configured to rotate in a vertical plane about a horizontal axis.

These and other features will be described in more detail below with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The included drawings are for illustrative purposes and serve only to provide examples of possible structures and operations for the disclosed inventive systems, apparatus, methods and computer program products for locating unmanned aerial vehicles (UAVs). These drawings in no way limit any changes in form and detail that may be made by one skilled in the art without departing from the spirit and scope of the disclosed implementations.

FIG. 1A shows a flowchart of an example of a method 100 for locating unmanned aerial vehicles (UAVs), performed in accordance with some implementations.

FIG. 1B shows a simplified block diagram of an example of a scanning apparatus 136, in accordance with some implementations.

FIG. 2 shows a simplified diagram of an example of a configuration of statically deployed scanning apparatuses in the vicinity of an airport runway, in accordance with some implementations

FIG. 3 shows a simplified diagram of an example of a scanning apparatus 300, in accordance with some implementations.

FIG. 4 shows another simplified diagram of an example of a scanning apparatus 400, in accordance with some implementations.

FIG. 5 shows example of a graph of signal strength of radio signals received by Ground Data Terminal (GDT) 208 of FIG. 2, in accordance with some implementations.

FIG. 6 shows an example of a simplified diagram of a scanning apparatus 600 mounted to a light pole 604 in an airport parking lot or near a runway, in accordance with some implementations.

FIG. 7 shows a block diagram of a simplified example of a system 700 for locating UAVs, in accordance with some implementations.

DETAILED DESCRIPTION

This disclosure describes some techniques, methods, systems, apparatus, and computer program products that can be used for detecting “Unmanned Aerial Vehicles” (UAVs). The techniques may be particularly, though not exclusively, applicable to detection of small UAVs, such as those weighing approximately 10 pounds or less, sometimes referred to as micro-UAVs, micro-drones, quad-copters or multi-rotors, and referred to herein below as micro-UAVs. Such micro-UAVs can be too small to detect using conventional Radio Detection And Ranging (RADAR) technology and can pose significant risks, which are difficult to mitigate using traditional techniques. For example, an undetected micro-UAV could be used to drop an explosive, chemical, or biological weapon, in a crowded location. Or, a micro-UAV flown at or near an airport, whether or not with nefarious intentions, could be a safety concern for commercial, civil or other aviation. Such risks are underscored by a recent spate of micro-UAV incursions near sensitive locations such as airports, governmental residences, military bases, and monuments.

Unfortunately, conventional technology, such as static non-directional antennae, can be unreliable when used to scan for micro-UAVs. For example, while a single non-directional antenna can receive downlink radio frequency signals from a micro-UAV, it cannot resolve the location of the micro-UAV. A configuration of four or more non-directional antennae at different locations might be usable to resolve a bearing of a micro-UAV by comparing differences in signal strength across each of the non-directional antennae. However, such a configuration cannot reliably be used to determine the elevation of a detected micro-UAV, using differences in signal strength alone.

Due to the relative ease of acquiring micro-UAVs and the difficulty of detecting them, a wide range of individuals can become amateur micro-UAV pilots, leading to potentially disastrous risks. By way of example, there is currently nothing to prevent a micro-UAV pilot with poor judgment or bad intentions from remotely flying a micro-UAV into the flight path of a commercial airliner taking-off or landing at an airport.

Some of the disclosed techniques can be used to mitigate some risks posed by micro-UAVs by reliably detecting and locating such micro-UAVs. Returning to the example of the preceding paragraph, two or more statically deployed scanning apparatuses, which are configured to detect micro-UAVs, can be placed in strategic locations near the airport runway. Such statically deployed scanning apparatuses are referred to herein as Ground Data Terminals (GDTs) and can be configured to sweep for micro-UAVs and collect bearing and elevation data for each detected micro-UAV, as described below. In some implementations, each GDT may include one or more directional antennae configured to receive 5.8 Gigahertz (GHz) radio frequency signals, the standard downlink frequency of micro-UAVs. Such directional antennae can be configured to rotate 360 degrees in two orthogonal planes such that each GDT can receive signals originating from any direction in the sky. The bearing and elevation of the micro-UAV relative to two or more GDTs can be detected and transmitted to a processing location such as a primary processor, or cloud-based distributed computing system, which can use triangulation techniques to locate the micro-UAV. The primary processor or cloud-based distributed computing system can then disseminate location information for the micro-UAV to appropriate parties, for example, air traffic control, aircraft, law enforcement or security to take corrective action. For example, an aircraft could be redirected to avoid a collision.

FIG. 1A shows a flowchart of an example of a method 100 for locating unmanned aerial vehicles (UAVs), performed in accordance with some implementations. FIG. 1A is described with reference to FIGS. 1B-5. FIG. 1B shows a simplified block diagram of an example of a scanning apparatus 136, in accordance with some implementations. FIG. 2 shows a simplified diagram of an example of a configuration of statically deployed scanning apparatuses (or GDTs) in the vicinity of an airport runway, in accordance with some implementations. FIG. 3 shows a simplified diagram of an example of a scanning apparatus, in accordance with some implementations. FIG. 4 shows another simplified diagram of an example of a scanning apparatus, in accordance with some implementations. FIG. 5 shows example of a graph of signal strength of radio signals received by GDT 208 of FIG. 2, in accordance with some implementations.

At 104 of FIG. 1A, a region 201 of airspace is scanned by two scanning apparatuses in the form of GDTs 208 and 212 of FIG. 2. In some implementations, a region of airspace can be scanned by more than two scanning apparatuses. However, one having skill in the art would appreciate that at least two scanning apparatuses are required to perform the triangulation techniques explained below in the context of 124 of FIG. 1. A wide variety scanning apparatuses can be used to scan a region of airspace, as described below. For example, some scanning apparatuses can be statically deployed in varying locations on the ground. As described above, such statically deployed scanning apparatuses are referred to herein as GDTs. Also or alternatively, scanning apparatuses can be dynamically deployed. For example, scanning apparatuses can be mounted on a vehicle, such as a commercial aircraft, as discussed below. Additionally, in some implementations, scanning apparatuses can be portable.

The inner workings of a scanning apparatus, such as a GDT, can vary across implementations. A simplified block diagram of an example of such a scanning apparatus 136 is shown in FIG. 1B. In some implementations, scanning apparatus 136 may include some (or all) of a number of components, such as directional antenna (or antennae) 140, processor(s) 144, network interface(s) 148, memory 152, rotation driving mechanism(s) 156, diversity receiver 162, amplifier(s) 168, global positioning system (GPS) 172, time-keeping device 176, power source 180, and enclosure 184, which are each discussed in further detail below.

Some components of scanning apparatus 136 can be deployed or configured in a variety of manners. For example, directional antennae 140 may be configured to receive signals from a micro-UAV. Scanning apparatus 136 may be equipped with multiple high-gain directional antennae configured to receive 2.4 Giga Hertz (GHz), and/or 5.8 GHz electromagnetic signals, which are standard uplink and downlink frequencies of micro-UAVs, respectively. Additionally, such antennae may be tunable to other radio frequency ranges in order to detect micro-UAVs operating in different frequency bands. By way of example, if micro-UAVs are operated with a downlink frequency of 933 MHz, directional antennae 140 can be configured to receive 933 MHz signals. Antennae 140 can rotate in a number of directions or planes to detect micro-UAVs or micro-UAV operators in a variety of locations, as discussed below. As such, the configuration of antennae 140 can vary greatly, as described below in the context of implementations shown in FIGS. 3 and 4, as well as other implementations.

FIG. 3 shows a simplified diagram of one such scanning apparatus 300, which is an example of a scanning apparatus 136 that includes three directional antennae 304-312. Scanning apparatus 300 includes directional antenna 304 and directional antenna 308, which are configured to rotate 360 degrees in a horizontal plane 316 to obtain bearing data for encroaching micro-UAVs, as described below. Directional antenna 304 and directional antenna 308 can be configured to receive signals within either the same or different angular ranges. Directional antenna array 312 (which could be one or more antennae) is configured to rotate 360 degrees in a vertical plane 320 in order to collect elevation data for encroaching micro-UAVs, as described below. One having skill in the art can appreciate that horizontal plane 316 and vertical plane 320 can be substantially orthogonal—e.g. the angle between horizontal plane 316 and vertical plane 320 need not be precisely 90 degrees.

The beamwidth of a directional antennae, such as directional antennae 304-312 can vary across implementations. For example, region 324 is a hypothetical beamwidth of directional antenna 304. An array of adjacently placed directional antennae may be used in place of a single directional antenna to increase beamwidth.

Alternatively, in some implementations, a scanning apparatus might contain only a single directional antenna. For instance, scanning apparatus 400 of FIG. 4 is an example of a scanning apparatus 136 that includes a single directional antenna. Scanning apparatus 400 includes directional antenna 404, which is configured to rotate from 0 to 90 degrees in a vertical plane 408 and 360 degrees in a horizontal plane 412. Since, directional antenna 404 can rotate such that it can scan the entire sky for micro-UAVs, directional antenna 404 can obtain both bearing and elevation data for encroaching micro-UAVs, as described below. Since scanning apparatus 400 is compact and contains only one directional antenna, it can be particularly useful in several implementations described below, such as an aircraft-mounted scanning apparatus, which is configured to locate micro-UAV operators.

In other implementations, a scanning apparatus may include an array of directional antennae, which may be statically deployed along a substantially vertical axis and rotatable up to 360° along a substantially orthogonal horizontal axis to scan for micro-UAV targets. Such an array of antennae can resolve an elevation of a micro-UAV at a given angle of rotation by comparing signal strength differences measured by each antenna. In other words, each statically deployed antenna can detect signals originating in different angular ranges. By way of example, a scanning apparatus might have a first, second, and third antenna statically deployed relative to a vertical axis at 15, 45, and 75 degree angles respectively. The first antenna might detect signals originating at an elevation between 0 and 29 degrees, the second antenna might detect signals originating at an elevation between 30 and 59 degrees, and the third antenna might detect signals originating at an elevation between 60 and 90 degrees.

As mentioned above, additional components of a scanning apparatus, such as scanning apparatus 136 of FIG. 1B, can vary greatly across implementations. For example, scanning apparatus 136 may include one or more rotation driving mechanisms 156, such as an electric motor, to drive the rotation of directional antennae and/or platforms to which such antennae are attached. Rotation driving mechanism 156 can be connected with a system of gears such that rotation driving mechanism 156 can cause the directional antennae 140 and/or platforms to which directional antennae 140 are attached to rotate.

Scanning apparatus 136 may also include a diversity receiver 162 such that scanning apparatus 136 can receive signals multiple directional antennae 140 and diversity receiver 162 can be used to measure the signal strength of such signals. In some implementations, an amplifier (or amplifiers) 168 can be used to amplify signals received by directional antennae 140. In some implementations, scanning apparatus 136 may include a magnetometer 163, which can provide a reference point, based on the earth's magnetic field, for collecting bearing data, which is discussed in further detail below.

Also or alternatively, scanning apparatus 136 may include a GPS 172 capable of providing data indicating the location of scanning apparatus 136. Scanning apparatus 136 may also include a time-keeping device 176 such as a Hobbs Meter, or a clock, or other device capable of measuring time.

In some implementations, scanning apparatus 136 may include one or more network interfaces 144 or a wireless or wired communication module to enable communication with other scanning apparatuses or with a primary processing module, as described below.

In some implementations, scanning apparatus 136 may also include memory 152 such as one or more storage media. Such storage may include either or both volatile or nonvolatile storage media and can provide non-transitory storage for computer readable instructions, data structures, program modules and other data for the operation of the scanning apparatus. Also or alternatively, scanning apparatus 136 may include one or more single or multi-core processors 144 configured to execute stored instructions.

In some implementations, scanning apparatus 136 may include an internal power supply 180 such as a battery or attached solar panels. Alternatively, scanning apparatus 136 may be connected with an external power supply, such as a light pole as discussed below in the context of FIG. 6.

In order to increase the durability of scanning apparatus 136, directional antennae 140 and other components of scanning apparatus 136 may be enclosed in enclosure 184. Enclosure 184 may be composed of a radio frequency transparent, corrosion-resistant, lightning-protected, and wind-resistant material such as fiberglass.

Scanning apparatuses can be deployed in a range of manners. For example, FIG. 2 shows a configuration of statically deployed scanning apparatuses, or more specifically GDTs 208-232, placed near an airport runway 202. Each GDT 208-232 of FIG. 2 can take the form of scanning apparatus 300 of FIG. 3, scanning apparatus 400 of FIG. 4, another type of scanning apparatus, or a combination of such scanning apparatuses. Such a configuration of GDTs can be used to scan portions of the sky near an airport for micro-UAVs, helping to avert collisions and near misses with airliners, as described above. For instance, in the example of FIG. 2, GDT 208 is located on or near an Air Traffic Control (ATC) tower, GDTs 212 and 216 are located along a typical approach corridor, GDTs 220 and 224 are located along a typical departure corridor and GDTs 228 and 232 are located on opposing ends of runway 202.

Returning to FIG. 1A, at 108, radio signals 204, of FIG. 2, are transmitted by micro-UAV 200 and received at GDTs 208 and 212. GDT 208 and GDT 212 have different locations, as discussed above. Similarly, as discussed above, GDTs 208 and 212 may be any combination of scanning apparatuses discussed above, or any other type of scanning apparatus that may include one or more directional antennae, which are configured to receive signals from micro-UAVs or micro-UAV operators.

At 112 of FIG. 1A, radio signals 204 are processed to determine a first location 252 of micro-UAV 200. Such processing can vary across implementations and determining the first location 252 of micro-UAV 200 can be accomplished in a number of manners. For instance, 116-124 of FIG. 1A offer an example illustrating several ways in which, radio signals 204 can be processed to determine a first location 252 of micro-UAV 200.

In some implementations, at 116, a signal strength of the radio signals 204 is determined by GDTs 208 and 212. For example, one or more directional antennae of GDTs 208 and 212 can be configured to receive 5.8 GHz radio signals, as described above. As such, radio signals 204, which have a 5.8 GHz frequency, can be received by such directional antennae. In some implementations, such antennae can be connected with an amplifier. Radio signals 204 can be transmitted from the antenna to an amplifier and on to a receiver, such as a diversity receiver, at which the signal strength of radio signals 204 can be measured. Alternatively, radio signals 204 can also be transmitted directly from an antenna to a receiver, without an intervening amplifier. Graph 500 of FIG. 5 shows an example of signal strength measurements of a directional antenna or array of directional antennae of GDT 208 throughout a single polar (or vertical) rotation.

In some implementations, at 120 of FIG. 1A, data indicating an angular relationship between locations of GDTs 208 and 212 and a detected micro-UAV 200 of FIG. 2 is generated. For example, a processor of GDTs 208 and 212 can process signal strength measurements determined at 112 of FIG. 1A to determine a location of a peak 5.8 GHz signal strength in the polar and azimuthal planes. In other words, GDT 208 can determine an elevation of a peak 5.8 GHz signal strength at θ₁ 236, as shown in FIG. 5. Along the same lines, GDT 208 can determine a bearing of a peak 5.8 GHz signal strength in the azimuthal plane at ϕ₁ 240. Since the standard uplink frequency of a micro-UAV is 5.8 GHz, GDT 208 can infer the presence of micro-UAV 200 at an elevation of θ₁ 236 and a bearing of ϕ₁ 240.

Alternatively, GDT 208 may not include a processor, but rather, GDT 208 might merely measure 5.8 GHz signal strength in the polar and azimuthal planes, and transmit such signal strength measurements to a primary processor or cloud-based distributed computing system, as described below. The primary processor or cloud-based distributed computing system can process the signal strength measurements, as described in the preceding paragraph, and determine the presence of micro-UAV 200 at an elevation and bearing of θ₁ 236 and ϕ₁ 240 respectively, with respect to GDT 208.

Using similar techniques, it can be determined by GDT 212, or by a primary processor or cloud-based distributed computing system, that micro-UAV 200 is at an elevation and bearing of θ₂ 244 and ϕ₂ 248 respectively, with respect to GDT 212.

In some implementations, a rate of rotation (also referred to herein as a slew rate) of a directional antenna (or antennae) of a scanning apparatus can be configured to vary throughout a rotation to increase accuracy in determining an angular relationship between the scanning apparatus and a micro-UAV. For instance, a directional antenna (or antennae) in a scanning apparatus can be configured to rotate slowly in a given rotation when the antenna (or antennae) is within a designated angular distance (e.g. within 10 degrees) of a detected micro-UAV. The antenna (or antennae) can rotate more quickly when the antenna (or antennae) is greater than the designated angular distance from the micro-UAV. By way of example, in a first cycle, GDT 208, of FIG. 2, detects micro-UAV 200 at an elevation of θ₁ 236 and a bearing of ϕ₁ 240, which can be recorded in a storage medium of GDT 208, as described above. Since micro-UAV 200 is unlikely to have moved much in the time of a given cycle, in the following cycle the recorded values of θ₁ 236 and ϕ₁ 240 in the storage medium of GDT 208 can trigger a processor of GDT 208 to cause GDT 208 to slow down its slew rate, sweeping at 0.5 Hz within 10 degrees of θ₁ 236 or ϕ₁ 240—the most likely location of micro-UAV 200. Since micro-UAV 200 is less likely to be more than 10 degrees away from θ₁ 236 or ϕ₁ 240, a processor of GDT 208 can cause GDT 208 to speed up its slew rate to 2 Hz when in a range of more than 10 degrees away from θ₁ 236 or ϕ₁ 240.

Returning to FIG. 1A, in some implementations, at 124, the angular relationship data of 120 are processed to determine the first location 252 of micro-UAV 200 of FIG. 2. For example, a primary processor or cloud-based distributed computing system can be configured to receive elevation and bearing data from GDTs 208 and 212 and process such data to determine a location of micro-UAV 200. By way of illustration, a primary processor can triangulate the position micro-UAV 200 based on the signal spikes discussed in the preceding paragraph. In other words, the primary processor can use standard geometry to determine, based on θ₁ 236, ϕ₁ 240, θ₂ 244, ϕ₂ 248, and the locations of GDT 208 and GDT 212, that there is a source emitting a 5.8 GHz signal originating at first location 252 where line 256 and line 260 meet. Since the downlink frequency of a standard micro-UAV is 5.8 GHz, the primary processor can infer that there is a micro-UAV at point 252.

In some implementations, a primary processor can be included as a part of one or more scanning apparatuses, such as a GDT. Also or alternatively, a primary processor can be a separate computing device, which is configured to communicate with scanning apparatuses, such as GDTs.

The manner in which GDTs communicate with each other and with a primary processor can vary across implementations. For example, a secure two-way communication channel such as a wired fiber-optic connection can be utilized. Also or alternatively, GDTs and primary processors can communicate through a variety of wireless channels such as via Bluetooth or via a WiFi local area network. Also or alternatively, communications exchanged between GDTs and the primary processor can be encrypted, for example using standard public-key cryptography or other techniques, for enhanced security.

In some implementations, at 128 of FIG. 1A, the first location 252 of micro-UAV 200 of FIG. 2 is disseminated to a variety of sites. For instance, the primary processor can communicate the coordinates of the micro-UAV to an Air Traffic Controller (ATC) such that the ATC can contact pilots of any approaching airliners as well as appropriate authorities. Also or alternatively, the coordinates of the micro-UAV could be communicated directly to an approaching airliner via an appropriate communications protocol, such as an existing Traffic Collision Avoidance System (TCAS) or Automated Dependent Surveillance-Broadcast (ADS-B.)

In some implementations, at 132 of FIG. 1A, a velocity of micro-UAV 200 of FIG. 2 is determined. For example, a primary processor can determine velocity data for an encroaching micro-UAV by averaging the change in coordinates of an encroaching micro-UAV over the time of two or more cycles of rotation of GDTs collecting bearing and elevation data for the encroaching micro-UAV. By way of example, a second location of micro-UAV 200 can be determined using the techniques described above in the context of 104-112 of FIG. 1A. The first location 252 and the second location of micro-UAV 200 can then be used to determine the velocity of micro-UAV 200. For instance, a primary processor can log a first time at which micro-UAV 200 was detected at the first location 252 and a second time at which micro-UAV 200 was detected at the second location. The primary processor can divide the distance between the first location 252 and the second location by the difference between the first and second times to get a magnitude of the velocity of micro-UAV 200. Similarly, the primary processor can determine the directional component of the velocity of micro-UAV 200 by determining the direction of the displacement of micro-UAV 200 between the first location 252 and the second location.

In some implementations, two or more UAVs can be tracked using the disclosed techniques. For instance, some of the disclosed techniques can be used for enhanced scanning of portions of the sky near a sensitive area for detection of multiple micro-UAVs at any given time. Redundant GDTs can be placed near a sensitive area to sweep for and follow multiple micro-UAVs. In one example, returning to FIG. 2, GDTs 208 and 212 might be tracking micro-UAV 200 and GDTs 232 and 216 might be tracking a further micro-UAV.

Alternatively, two scanning apparatuses can be used to track more than one micro-UAV. By way of example, GDTs 208 and 212 can track both micro-UAV 200 and a further micro-UAV. In this case, GDTs 208 and 212 might have redundant antennae if enhanced tracking capabilities are desired.

In some implementations, two or more scanning apparatuses might be placed in the same or similar location, for increased ability to track two or more UAVs. For example, GDT 208 may include more than one scanning apparatus, such as scanning apparatus 300 of FIG. 3, scanning apparatus 400 of FIG. 4, or another scanning apparatus or combination of scanning apparatuses. As such, if GDT 208 includes more than one scanning apparatus, each scanning apparatus of GDT 208 can be used to exclusively track a different micro-UAV at a given time by slowing down its slew rate in the angular vicinity of the tracked micro-UAV, as described above.

In some implementations, GDTs, or other scanning apparatuses, can be placed in strategic locations to take advantage of existing structures. For example, FIG. 6 shows an example of a simplified diagram of a scanning apparatus 600 mounted to a light pole 604 in an airport parking lot or near a runway, in accordance with some implementations. For instance, GDT 212 of FIG. 2 might include scanning apparatus 600 of FIG. 6. Placing a scanning apparatus in high location, such as on top of light pole 604, relative to the ground can prevent tampering and aid in avoiding obstructions. Additionally, this placement could allow scanning apparatus 600 to use an already available power source of light pole 604.

One having skill in the art would appreciate that the disclosed techniques can be applied in a diverse array of contexts, a few of which are described below. More specifically, a variety of scanning apparatuses, such as scanning apparatus 300 of FIG. 3, scanning apparatus 400 of FIG. 4, or another scanning apparatus, can be statically or dynamically deployed in a heterogeneous set of locations and can be used to detect and locate micro-UAVs using some of the disclosed techniques, described above. For instance, FIG. 7 shows a block diagram of a simplified example of a system 700 for locating UAVs, in accordance with some implementations. In FIG. 7, a signal source 704, such as a micro-UAV, emits electromagnetic signals 708. Two or more receiving modules 712, such as any of the scanning apparatuses described above, can be configured to receive signals 708 and transmit bearing and elevation data to a primary processing module 716 using the techniques described above. Primary processing module 716 can process the bearing and elevation data to determine a location of signal source 704 and pass the location to a transmission module 720. The transmission module 720 can transmit the location to a variety of sites, as described above.

In some implementations, system 700 can be deployed near a sensitive building, such as the White House, or a national monument, such as Mount Rushmore or the Eiffel Tower. By way of example, receiving modules can 712 be placed in a perimeter around a sensitive building or monument.

Also or alternatively, system 700 can be deployed in a variety of other locations. For instance, system 700 may be deployed near a prison to prevent incursions of micro-UAVs, which could be used to remotely deliver drugs of weapons into the prison. Similarly, system 700 can be temporarily deployed at events, such as the Super Bowl® or a presidential speech, using portable scanning apparatuses, as described below. By way of illustration, one or more scanning apparatuses might be placed near a building such as the White House. For example, a single apparatus 400 of FIG. 4 might be placed on top of such a building to detect micro-UAVs, and determine a bearing and/or elevation of such micro-UAVs as they approach the building, as described above. If a micro-UAV is detected, the authorities can be alerted, the building can be evacuated, and the micro-UAV can be shot down (or otherwise eliminated) as it enters the vicinity of the building.

On the other hand, a configuration of two or more scanning apparatuses 300 might be place near a building to detect an approaching micro-UAV, and determine accurate three-dimensional coordinates of the approaching micro-UAV, using some of the techniques discussed above in the context of 104-124 of FIG. 1A. In this case, the scanning apparatuses might be in communication with a system configured to automatically shoot down (or otherwise eliminate) the micro-UAV.

As mentioned above scanning apparatuses can be dynamically deployed. For example, scanning apparatus 400 of FIG. 4 can be mounted near the nose of a commercial aircraft, such as a Boeing® 747, an Airbus® A320, an Embraer® ERJ 145, a Fokker® f100, an Irkut® MC-21, etc.

Because such an aircraft can be located high enough to scan radio signals on the ground without being impeded by obstacles such as buildings, mountains, hills, etc., a single aircraft mounted scanning apparatus can be used to locate ground-based micro-UAV operators. By way of example, scanning apparatus 400 can be mounted on a Boeing®, which is approaching an Airport. In this scenario, directional antenna 404 can be configured to receive 2.4 GHz signals—the standard uplink frequency of a micro-UAV. As such, using some of the techniques described above, scanning apparatus 400 can be used to determine the bearing and elevation of a micro-UAV operator on the ground relative to the 747. Since micro-UAV is being operated from the ground, bearing and elevation data from a single scanning apparatus can be sufficient in and of itself to locate the micro-UAV operator without a further signal for triangulation. In other words, since the micro-UAV operator need only be located in two dimensions since she is near to the ground, her bearing and elevation relative to the 747 is sufficient to determine her location. As such, the pilot of the 747 can disseminate the micro-UAV operator's location to the authorities, so that she can be apprehended.

In some implementations, scanning apparatuses can be configured to reject known emissions. By way of example, if a known micro-UAV, or other radio frequency emission source such as a baby monitor, that poses no danger is in the vicinity of GDT 208, GDT 208 can determine, based in information in one or more of its storage media that any signal received from the location of the known micro-UAV should be ignored by GDT 208. As such, a processor of GDT 208 can cause GDT 208 to filter any radio signal originating from the known micro-UAV.

In some implementations, scanning apparatuses, such as those described above, can be made portable. For example, as described above, a scanning apparatus may include a Global Positioning system (GPS). As such even if the scanning apparatus is moved to a new location, the new location of the scanning apparatus can be transmitted to a primary processor, without the need to manually alert the primary processor of the scanning apparatus' new location.

In some implementations, the velocity of a detected micro-UAV can be determined using a single scanning apparatus by analyzing the strength of a signal originating from the micro-UAV as the micro-UAV approaches the scanning apparatus. For example, the signal strength at a given point of a radio signal originating from a source has an inverse-squared relationship with the radial distance between the source and the point. As such, a scanning apparatus can determine the radial velocity of a moving micro-UAV by analyzing the strength of the signal originating from the micro-UAV over time. The angular components of the velocity of the micro-UAV can be determined by measuring the changes in bearing and elevation of the micro-UAV over time.

While various specific implementations have been particularly shown and described, it will be understood by those skilled in the art that changes in the form and details of the disclosed implementations may be made without departing from the spirit or scope of this disclosure. In addition, although various advantages, aspects, and objects have been discussed herein with reference to various implementations, it will be understood that the scope of this disclosure should not be limited by reference to such advantages, aspects, and objects. 

What is claimed is:
 1. A method for tracking unmanned aerial vehicles (UAVs), the method comprising: scanning a region of airspace with two scanning apparatuses, each scanning apparatus comprising one or more directional Radio Frequency (RF) antennae, the two scanning apparatuses having different locations; receiving first radio frequency signals emitted by a first UAV at each of the two scanning apparatuses, a frequency of the first radio frequency signals being a downlink frequency of the first UAV; processing, based on an angular relationship between the locations of the scanning apparatuses and the first UAV, the first radio frequency signals to determine a first location of the first UAV; receiving second radio frequency signals emitted by a second UAV at a first one of the two scanning apparatuses; and tracking both the first UAV and the second UAV.
 2. The method of claim 1, wherein processing the first radio frequency signals to determine the first location of the first UAV comprises: determining a signal strength associated with a the first radio frequency signals at each of the scanning apparatuses; generating, using the signal strength, first data indicating an angular relationship between the locations of the scanning apparatuses and the first UAV; processing, using the locations of the scanning apparatuses, the first data to determine the first location of the first UAV
 3. The method of claim 1, further comprising: determining a second location of the first UAV; and determining, using the first and second location of the UAV, a velocity of the first UAV.
 4. The method of claim 1, wherein: one or more of the directional antennae of the first scanning apparatus are configured to rotate in a first plane about a first axis; and one or more of the directional antennae of the first scanning apparatus are configured to rotate in a second plane about a second axis.
 5. The method of claim 4, wherein the first plane is substantially orthogonal to the second plane.
 6. The method of claim 4, wherein a rate of rotation of a first one of the directional antennae of the first scanning apparatus is configured to vary throughout a rotation.
 7. The method of claim 6, wherein the rate of rotation of the first directional antenna is based on a recent location of the first and/or second UAV.
 8. The method of claim 1, further comprising: receiving third radio frequency signals at the first scanning apparatus; determining that the third radio frequency signals are associated with a designated source; and filtering, responsive to determining that the third radio frequency signals are associated with the designated source, the third radio frequency signals.
 9. The method of claim 1, wherein the UAV has a weight of 10 pounds or less.
 10. The method of claim 1, wherein the first scanning apparatus is mounted to a light pole.
 11. The method of claim 10, wherein the light pole includes a power source connected with the first scanning apparatus.
 12. A system for tracking UAVs, the system comprising: a plurality of ground data terminals, each ground data terminal comprising an array of one or more directional antennae configured to receive radio frequency signals having a designated frequency, the array of directional antennae having a spatial configuration, each ground data terminal being configured to: receive radio frequency signals associated with one or more UAVs, a frequency of each radio frequency signal being a downlink frequency of a corresponding UAV; determine a signal strength associated with each of the radio frequency signals; and generate, using the signal strength and the spatial configuration, data indicating an angular relationship between a location one of the plurality of ground data terminals and the corresponding UAV; one or more processors in communication with each of the ground data terminals, the one or more processors operable to: receive data from at least two of the plurality of ground data terminals; process, using locations of the at least two ground data terminals, the data from the at least two ground data terminals determine locations of a first UAV and a second UAV; track both the UAV and the second UAV.
 13. The system of claim 12, wherein the plurality of ground data terminals comprises: one or more ground data terminals positioned within an approach corridor of an airport runway; one or more ground data terminals positioned within a departure corridor of the airport runway; and one or more ground data terminals positioned at an end of the airport runway.
 14. The system of claim 12, the one or more processors further operable to: determine a second location of the first UAV; and determine, using the first and second location of the first UAV, a velocity of the first UAV.
 15. The system of claim 12, wherein: one or more of the directional antennae of a first one of the ground data terminals are configured to rotate in a first plane about a first axis; and one or more of the directional antennae of the first ground data terminal are configured to rotate in a second plane about a second axis.
 16. The system of claim 15, wherein a rate of rotation of a first one of the directional antennae of the first ground data terminal is configured to vary throughout a rotation.
 17. The system of claim 16, wherein the rate of rotation of the first directional antenna is based on a recent location of the UAV.
 18. A computer program product comprising computer-readable program code to be executed by one or more processors when retrieved from a non-transitory computer-readable medium, the program code including instructions configured to cause: scanning a region of airspace with two scanning apparatuses, each scanning apparatus comprising one or more directional Radio Frequency (RF) antennae, the two scanning apparatuses having different locations; processing first radio frequency signals emitted by a first UAV at each of the two scanning apparatuses, a frequency of the first radio frequency signals being a downlink frequency of the first UAV; processing, based on an angular relationship between the locations of the scanning apparatuses and the first UAV, the first radio frequency signals to determine a first location of the first UAV; processing second radio frequency signals emitted by a second UAV at a first one of the two scanning apparatuses; and tracking both the first UAV and the second UAV.
 19. The computer program product of claim 18, wherein processing the first radio frequency signals to determine the first location of the first UAV comprises: determining a signal strength associated with the first radio frequency signals at each of the scanning apparatuses; generating, using the signal strength, first data indicating an angular relationship between the locations of the scanning apparatuses and the first UAV; processing, using the locations of the scanning apparatuses, the first data to determine the first location of the first UAV.
 20. The computer program product of claim 18, the program code including further instructions configured to cause: determining a second location of the first UAV; and determining, using the first and second location of the UAV, a velocity of the first UAV. 